Headphones, as a single headphone for one ear, or a set of two with one headphone for each ear, are in popular use for listening to music, speech during a mobile phone call, or other audio. When using a headphone of any type, whether in the ear, over the ear or around the ear, the user is acoustically cut off from the surrounding environment. The user experiences a loss of high-frequency sound components due to passive attenuation of the ear cup or earbud.